HP 6125XLG R2306-HP 6125XLG Blade Switch IP Multicast Configuration Guide - Page 22
How IGMP snooping works, General query, IGMP report
View all HP 6125XLG manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 22 highlights
Timer Dynamic member port aging timer Description Message received before the timer expires When a port dynamically joins a multicast group, the switch starts or resets an aging timer for the port. When the timer expires, the dynamic member port ages out. IGMP membership report. Action after the timer expires The switch removes the port from the IGMP snooping forwarding table. NOTE: In IGMP snooping, only dynamic ports age out. Static ports never age out. How IGMP snooping works The ports in this section are dynamic ports. For information about how to configure and remove static ports, see "Configuring static ports." IGMP messages are general query, IGMP report, and leave message. An IGMP snooping-enabled switch performs differently depending on the message. General query The IGMP querier periodically sends IGMP general queries to all hosts and routers identified by the address 224.0.0.1 on the local subnet to determine whether any active multicast group members exist on the subnet. After receiving an IGMP general query, the switch forwards the query to all ports in the VLAN except the port that received the query. The switch also performs one of the following actions: • If the receiving port is a dynamic router port in the router port list, the switch restarts the aging timer for the port. • If the receiving port does not exist in the router port list, the switch adds the port to the router port list, and starts an aging timer for the port. IGMP report A host sends an IGMP report to the IGMP querier for the following purposes: • Responds to queries if the host is a multicast group member. • Applies for a multicast group membership. After receiving an IGMP report from the host, the switch forwards it through all the router ports in the VLAN, resolves the address of the reported multicast group, and performs one of the following actions: • If no forwarding entry matches the group address, the switch creates a forwarding entry for the group, adds the receiving port as a dynamic member port to the forwarding entry, and starts an aging timer for the port. • If a forwarding entry matches the group address, but the receiving port is not in the forwarding entry for the group, the switch adds the port as a dynamic member port to the forwarding entry, and starts an aging timer for the port. • If a forwarding entry matches the group address and the receiving port is in the forwarding entry for the group, the switch restarts the aging timer for the port. In an application with a group filter configured on an IGMP snooping-enabled switch, when a user requests a multicast program, the user's host initiates an IGMP report. After receiving this report, the 15